Using a stand mixer fitted with the paddle attachment, cream the room temperature butter and both sugars together on medium speed until smooth. Add the egg and mix on high until combined, about 1 minute. Add the vanilla and continue to mix on high until combined. Scrape down the sides and bottom of the bowl. Set aside.

In a medium bowl, toss together the flour, baking soda, cinnamon and salt. Add the flour mixture to the butter mixture on the low setting until combined. While the mixer is on, add in the oats, raisins, and pecans. The dough is going to be sticky and thick. Chill the dough covered with plastic wrap for 30 minutes minimum and 60 minutes max. If you'd like to prepare the dough a few days ahead of time, allow the cookie dough to sit at room temperature for 30-40 minutes before scooping and baking.

Position 2 racks in the center of the oven and preheat the oven to 350 degrees F. Line two baking trays with parchment paper or silicone mats. Roll 1 1/2 tablespoons of cookie dough into a ball and place them a couple inches apart on the baking sheet. Bake for 9-10 minutes or until they start to get lightly brown around the edges. The centers will look undone, this is fine. Let cool on tray for 5 minutes before transferring to a wire cooling rack.

Cookies can be stored in an air tight container, at room temperature for up to 5 days.